1. Warm olive oil in a large deep skillet or Dutch oven over medium-high heat.

2. Add ground beef and diced onion, then cook for 5 to 7 minutes until the beef is browned and the onion is soft.

3. Drain excess grease if needed, leaving a small amount in the pot for flavor.

4. Stir in garlic and cook for 30 seconds until fragrant.

5. Add tomato paste and cook for 1 minute, stirring it into the beef.

6. Pour in crushed tomatoes and beef broth, then add Italian seasoning, paprika, red pepper flakes, salt, and black pepper.

7. Stir in the pasta shells and bring the mixture to a gentle boil.

8. Reduce heat to medium-low, partially cover, and simmer for 10 to 13 minutes, stirring often, until the shells are tender.

9. Lower the heat and stir in the heavy cream until warmed through.

10. Add cheddar cheese and Parmesan cheese a little at a time, stirring until melted and creamy.

11. Taste and adjust seasoning, then garnish with fresh parsley and serve warm.